Well obviously if you fail on the scenario questions part, you aren't choosing the right answers.
If you really want a job, stop being so picky by just going into retail. Coffee shops and pubs are constantly looking for someone. Warehouses will usually hire anyone on the spot. You could also get a cleaning job, they usually have nice short shifts 1-3 hours and either really early 6-7am before places open or late in the evening 6-7pm after places have closed. So you can even do it while studying.